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Standard User ambernaut
(learned) Tue 22-Dec-15 14:57:37
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When Does Interleave Depth Become A Concern?


[link to this post]
 
After having ADSL2+ for over 5 years running a connection of 15Mb, I recently took the plunge for Fibre Large on TT, the offer was sweet. All is fine on the surface.
At first I had a 68Mb connection running a DL interleave depth of 1. All good and various download tests matched it.
I had some landline phone calls a few days later, ringing was intermittent and cut out, then I did manage to answer and the rattling and clicking on the line was a surprise, never had it before, It continued next day too.
The internet was still swift, but picking up the phone killed the connection every time. I put a call in to TT. Next day the line was working as normal again. TT got in touch, said they tested the line and couldnt find a fault.
So somehow it was quietly fixed. Connection solid ever since.
I checked my broadband stats on the router and now the connection was around 65Mb. No big deal.
The DL interleave depth was now 2547. Been that for over a week (see stats below).
I've little knowledge of this (applied by DLM for breaking up data packets for improved transfer?), is that a high value? Will it cause any issues for gaming ping rates etc?
From Router:-
Line Quality
Upstream line rate (kbit/s):
20000
Downstream line rate (kbit/s):
65242
Upstream noise safety coefficient (dB):
6
Downstream noise safety coefficient (dB):
7.8
Upstream interleave depth:
277
Downstream interleave depth:
2547
Line standard:
VDSL2
Upstream line attenuation (dB):
0.1
Downstream line attenuation (dB):
9.3
Upstream output power (dBm):
7.3
Downstream output power (dBm):
12.2
Channel type:
Interleaved
DSL up-time:
8 days 6 hours 43 minutes 42 seconds

If DLM has added this due to the noisy line, will it eventually drop off again?
Or maybe this is how the noise was fixed? DOes the stats reveal anything to the trained eye? Is it something I should expect and carry on about my day without fussing about it??!
Never had any issues internally or externally in over 5 years, only day after fibre switchover from ADSL2+.

Hope you can shed some light on my concerns and hopefully educate me a little too.
Andy

Claranet -> Pipex -> Nildram -> IDNet -> BT -> TT
Standard User WWWombat
(knowledge is power) Tue 22-Dec-15 19:16:25
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Re: When Does Interleave Depth Become A Concern?


[re: ambernaut] [link to this post]
 
In reply to a post by ambernaut:
If DLM has added this due to the noisy line, will it eventually drop off again?


That should indeed happen. The speed with which it disappears depends on just how free of errors your line has become, and can take a few days, or over a month.

Having an interleaving depth of the order of thousands means the old-style DLM intervention has happened, where FEC and interleaving have been turned on - usually in response to seeing more than 1440 errored seconds in a 24 hour period, although the threshold might be 2880 if your ISP orders lines with the "speed" profile. Once intervened, you'll see speed drops and latency increases of the order of 8-16ms.

Huawei cabinets allow for gentler DLM intervention, using something called G.INP, or re-transmission. Where available, this is pretty much turned on almost as a default. There interleaving will be in the tens, with latency delays of tenths of milliseconds.

Or maybe this is how the noise was fixed?


Nope. It won't be that way around.

Never had any issues internally or externally in over 5 years, only day after fibre switchover from ADSL2+.


It could be that a bad joint was made in the cabinet, and it has subsequently been disturbed by another engineer moving cables around. Pay attention for the return of such noises. They almost always start out in an intermittent fashion, and are hard to solve.

Is it something I should expect and carry on about my day without fussing about it??!


Drops in speed caused by crosstalk - noise from other subscribers - should be expected as take-up increases. It is annoying to see, but has to be expected.

If this happens, it can increase the error rate too - and possibly enough to trigger DLM for good. If it happens, then you might want to take steps to make your line as good as it can be, but there is often little you can do.

It isn't worth being obsessed with.

Hope you can shed some light on my concerns and hopefully educate me a little too.
Andy


Your stats, unfortunately, miss out most of the interesting things - especially the all-important error rate.
Standard User bewA
(regular) Wed 23-Dec-15 11:14:09
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Re: When Does Interleave Depth Become A Concern?


[re: WWWombat] [link to this post]
 
Just to add to my experience of this.

I'm about 800mtrs from the fibre cabinet. I was one of the first customers to be connected to the cabinet. The speed started at 42mbps. It was awesome for the first couple of days. after a period of time my line developed some noise issues and DLM went nuts reducing my speed to 15mbps (at worse). I was on TalkTalk's Fibre Large product.
For what it's worth i had ADSL with 2.5mbps (on a good day!)

I had interleaving hammering the line at 1500+ on the downstream and some number on the upstream!

After persuading the Openreach engineer on the second visit they did a DLM reset but i was not able to get any more than 30mbps. So as the box has filled up the bandwidth has reduced which will be down to crosstalk!


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